3.55 gears rpm?

[rrab1]

Hi all, Took fifth wheel from St. Loius to K. C. and back this weakend and @65mph in od my rpm 1750-1775 so my question is this,alot of guy's here say to keep rpm up in 2000 range so should I turn od off? At no time did the trans jump in out of over drive,got 12 mpg and had a good time K. C. Thanks Don

 

[rluft]

Sounds like the numbers I get. That is why I would rather have the 4. 10 gears. I run 70 mph to keep the revs up and keep it in OD, although I often would rather drive slower. I believe the transmission developes more hydraulic pressure above 1600, so I keep the motor running above that when towing.

 

[dodgeguy44]

Stock transmission probably won't like it much but the Goerend transmission you have should have the parts in it to withstand the torque to a degree. Just don't pull a long hill with it in OD. Cruising should work great and get way better fuel economy than higher RPM.

 

[rrab1]

Thank's for the reply's Don

 

[nps]

I don't like towing above 65mph, and with 3. 54 gears, 6 speed, and 35" tires that puts me just above 1600 rpm. My motor is happy all day long.



Speeding up to put the motor into the 'most efficient' rpm will only increase wind resistance and decrease mpg. Maybe I could drop into 5th to get it at 2000 rpm, but that will just decrease mpg too.

 

[rrab1]

nps, Same here truck just seems happy @65mph and 1750 rpm and I'm comfortable at 65 too, but you read so much here about keeping the rpm's up around 2000 so I was woundering If I was doing wrong? Don

 

[nps]

nps, Same here truck just seems happy @65mph and 1750 rpm and I'm comfortable at 65 too, but you read so much here about keeping the rpm's up around 2000 so I was woundering If I was doing wrong? Don

Nope - you're doing just fine. I've challenged some of the 2000 rpm gang in the past to justify why mpg goes down when I follow their advice, but silence is the only response. Cummins says not to lug the motor, and defines lugging as the inability of the motor to generate power to accelerate the vehicle. I think we all know what that means and sounds like. So happy towing.

 

[TowPro]

In my 2006 manual, they say "running at WOT for more then 30 seconds at rpm's lower then peak torque". But they left out that RPM.



My 98 with 3:55's and 5 speed got around 3 MPG better then my 2002 auto 4:10's towing 10,000 lbs.



But the 02 was a dually which has to lower MPG some. Now the 2006 is a manual and the MPG is already up to what my 98 was doing towing the same weight (put it runs the same RPM as the auto 4:10's) so I bet the real problem was the Auto trans killing my MPG.



Plus even with 4:10's the auto trans was always kicking in and out of OD at 65mph.

 

[nps]

In my 2006 manual, they say "running at WOT for more then 30 seconds at rpm's lower then peak torque". But they left out that RPM.

Guess you have to put it on a dyno to know how to drive it huh? :-laf